1. Field of the Invention
The present invention relates to a composite semiconductor device in which driver circuits and elements driven by the driver circuits, an LED head that incorporates the semiconductor composite semiconductor device, and an image forming apparatus that incorporates the LED head.
2. Description of the Related Art
An electrophotographic printer incorporates an exposing unit that includes conventional composite semiconductor devices. The conventional composite semiconductor device includes a semiconductor substrate on which thin film wiring patterns are formed and the integrated driver circuits are formed on the semiconductor substrate. Thin film type LED arrays, fabricated on another substrate and released from the substrate, are bonded onto the region under which the driver circuits are not formed on the semiconductor substrate, and are electrically connected to the driver circuits via the wiring pattern.
An LED array incorporated in an LED head includes a large number of light emitting diodes (LEDs). A number of wirings are required for electrically connecting the LED arrays to the driver circuits. The LED arrays and the wirings occupy a large area outside of the area in which the driver circuits are formed. Consequently, a composite semiconductor device is difficult to be miniaturized.